Geotechnical land suitability assessment using spatial multi-criteria decision analysis

Abstract

Decision making is a thought-provoking issue in complex engineering problems, and it contains many parameters and alternatives inherently. Multi-criteria decision analysis (MCDA) is a common method to solve the problems involving many uncertainties, and it is employed here for answering some geotechnical issues. Soil type, underground water table (UWT), standard penetration test (SPT) (N) blow numbers, and shear wave velocity (V s) have been used to sort out the settlement suitability of the municipal area by means of MCDA and geographic information systems (GISs). Each data set was classified into 10 groups and graded based on it. A soil classification map was constructed using Voronoi cells. The Kriging interpolation method was employed to draw the other maps. The study area was allocated into five zones ranging from very favorable to very unfavorable. The very favorable and favorable zones are southern, southwestern, and northern parts of the study area. Firm units with high bearing capacity are outcropped on these areas. Moreover, the UWT is deep enough to interact with structures. On the contrary, the very unfavorable and unfavorable zones are located around the central part of the study area where the altitude is very low. Therefore, the soils have higher fine contents which commonly have low bearing capacity and exhibit high ground amplification when they are encountered with UWT. The faults and creeks, crossed the study area, were enclosed and marked as very unfavorable. It is because of the Turkish infrastructure regulations against flooding and ground rupture risks. The moderate zones fall within the best and the worst zones. The results prove that the spatial multi-criteria decision analysis (SMCDA) descriptions match the perception of the geotechnical assessments. The study has verified that the method can be employed successfully in the geotechnical microzoning studies.